The Australian number one began slowly, and was forced to save two set points against Zhang as he clawed his way back from being 5-3 down.
Zhang, who is 190th in the world rankings, appeared to be closing in on the set as he took a 2-0 lead in the tie break, but Tomic eventually won it 7/4.
The 20-year-old then broke Zhang's serve early in the second set and never looked to be in danger as he sealed victory with the scores at 7-6(7/4) 6-4.
Tomic is number 55 in the world rankings and considered one of the rising young guns of men's tennis. However, he has developed a bad boy reputation, largely because of the actions of his father and coach.
John Tomic received an eight-month suspended jail sentence earlier this month for headbutting his son's former training partner, Thomas Drouet, breaking his nose and knocking him out in a May assault outside a Madrid hotel.
The assault led to him being banned from a series of major tennis tournaments by the ATP.
It was a disappointing end to the China Open for Zhang, who was the home crowd star in Beijing last year when he knocked out France's Richard Gasquet in the second round.
The Chinese number one could have faced a re-match against Gasquet if he had overcome Tomic. However, the Australian will instead play the fifth seed in the second round if Gasquet wins his first-round match against German Florian Mayer.
In the women's competition, it was a successful day for the three Serbian players, who all overcame the first hurdle in Beijing.
Eighth seed Jelana Jankovic needed three sets to overcome Russian Anastasia Pavlyuchenkova, but finally defeated her opponent within two hours at 1-6, 6-4, 6-0. Compatriot Ana Ivanovic claimed victory over Italian Flavia Pennetta 7-6 (11/9), 6-1.
Bojana Jovanovski rounded off a hat-trick for the Serbians, claiming victory over Romanian Sorana Cirstea 6-3, 6-2.
The other early game saw Canadian Eugenie Bouchard beat Slovakian Magdalena Rybarikova 6-4, 6-1.
Results from the China Open in Beijing on Monday (x denotes seeding):
Bernard Tomic (AUS) bt Zhang Ze (CHN) 7-6 (7/4), 6-4
Fabio Fognini (ITA) bt Tommy Robredo (ESP) 7-5, 4-6, 6-3
Roberto Bautista Agut (ESP) bt Grigor Dimitrov (BUL) 6-4, 6-2
Philipp Kohlschreiber (GER) bt Albert Montanes (ESP) 7-5, 1-6, 7-6 (7/4)
Lleyton Hewitt (AUS) bt Tommy Haas (GER x7) 7-6 (8/6), 6-3
Ana Ivanovic (SRB x14) bt Flavia Pennetta (ITA) 7-6 (11/9), 6-1
Jelana Jankovic (SRB x8) bt Anastasia Pavlyuchenkova (RUS) 1-6, 6-4, 6-0
Bojana Jovanovski (SRB) bt Sorana Cirstea (ROM) 6-3, 6-2
Eugenie Bouchard (CAN) bt Magdalena Rybarikova (SVK) 6-4, 6-1
Galina Voskoboeva (KAZ) bt Sharon Fichman (CAN) 6-4, 6-3
Svetlana Kuznetsova (RUS) bt Hsieh Su-Wei (TPE) 6-1, 6-1
Zhang Shuai (CHN) bt Peng Shuai (CHN) 6-3, 6-3
Andrea Petkovic (GER) bt Victoria Azarenka (BLR x2) 6-4, 2-6, 6-4
Polona Hercog (SLO) bt Monica Puig (PUR) 6-1, 6-4
Sara Errani (ITA x5) bt Misaki Doi (JPN) 6-3, 6-2
Lucie Safarova (CZE) bt Kaia Kanepi (EST) 6-3, 6-3